diff --git a/Lib/test/_test_multiprocessing.py b/Lib/test/_test_multiprocessing.py
index 8f60122cb512e8..6539f250c271a1 100644
--- a/Lib/test/_test_multiprocessing.py
+++ b/Lib/test/_test_multiprocessing.py
@@ -4147,6 +4147,13 @@ def test_shared_memory_cleaned_after_process_termination(self):
                                      " a process was abruptly terminated.")
 
             if os.name == 'posix':
+                # Without this line it was raising warnings like:
+                #   UserWarning: resource_tracker:
+                #   There appear to be 1 leaked shared_memory
+                #   objects to clean up at shutdown
+                # See: https://bugs.python.org/issue45209
+                resource_tracker.unregister(f"/{name}", "shared_memory")
+
                 # A warning was emitted by the subprocess' own
                 # resource_tracker (on Windows, shared memory segments
                 # are released automatically by the OS).
diff --git a/Misc/NEWS.d/next/Tests/2021-09-15-23-32-39.bpo-45209.55ntL5.rst b/Misc/NEWS.d/next/Tests/2021-09-15-23-32-39.bpo-45209.55ntL5.rst
new file mode 100644
index 00000000000000..4c3bed0983b899
--- /dev/null
+++ b/Misc/NEWS.d/next/Tests/2021-09-15-23-32-39.bpo-45209.55ntL5.rst
@@ -0,0 +1,2 @@
+Fix ``UserWarning: resource_tracker`` warning in
+``_test_multiprocessing._TestSharedMemory.test_shared_memory_cleaned_after_process_termination``